The functional identity of the active centres of transketolase.

Direct determination of the number of catalytically active molecules of the coenzyme in holotransketolase (sedoheptulose-7-phosphate:D-glyceraldehyde-3-phosphate glycoaldehydetransferase, EC 2.2.1.1) has corroborated our previous data indicating that in the native enzyme there are two active centres. They have been provided to be functionally identical. It has been shown that the decrease in the specific activity of transketolase during its storage is due to inactivation of one of the active centres, having a lower affinity for the coenzyme. The second active centre retains thereby its full catalytic activity.